roll forging manufacturer
Roll forging is a forming technique that utilizes opposing rolls to shape a metal part. Even though roll forging uses rolls in order to accomplish the deformation of the material it is classified as a forging process and not a rolling process. More similarly to forging than rolling, it is a discrete process and not a continuous one. Roll forging is usually performed hot. The precisely shaped geometry of grooves on the roll form the part to the required dimensions. The forming geometry of the rolls used to forge parts is only present over a portion of the roll's circumference. Only part of a full revolution of a roll is needed to forge the work piece. Typically in manufacturing industry the forming geometry on the rolls may occupy from one quarter to three quarters of the roll's circumference.The production of forged rings is often performed by a process called ring rolling on rolling mills. These mills vary in size to produce rings with outside diameters of just a few inches to over 300" and in weights from a single pound up to over 300,000 pounds.
The process starts with a circular preform of metal that has been previously upset and pierced (using the open die forging process) to form a hollow "donut". This donut is heated above the recrystallization temperature and placed over the idler or mandrel roll. This idler roll then moves under pressure toward a drive roll that continuously rotates to reduce the wall thickness, thereby increasing the diameters (I.D. and O.D.) of the resulting ring.
Seamless rings can be produced in configurations ranging from flat, washer-like parts to tall, cylindrical shapes, with heights ranging from less than an inch to more than 9 feet. Wall thickness to height ratios of rings typically range from 1:16 up to 16:1, although greater proportions can be achieved with special processing. The simplest, and most commonly used shape is a rectangular cross-section ring, but shaped tooling can be used to produce seamless rolled rings in complex, custom shapes with contours on the inside and/or outside diameters.